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Note. —, No data. Size of pervalvar and transapical axes varies along the cell length in girdle as well as in valve views (Plate 53); the ranges given in Table 65 indicate the variation along the apical axis of the particular species.

Note. —, No data. Size of pervalvar and transapical axes varies along the cell length in girdle as well as in valve views (Plate 53); the ranges given in Table 65 indicate the variation along the apical axis of the particular species.

2b. Valve width almost the same from head pole until somewhat enlarged for a short distance about one-third from wedge-shaped, blunt-pointed foot pole. Cells in star or fan-shaped colonies

L. pacificumn (Cupp) Hasle comb. nov.

Distribution:

L. delicatulum—warm water region to temperate—off Portugal, NW Africa, Mediterranean, Gulf of Mexico, Indian Ocean, off California, South Pacific.

L. elongatum—warm water region—Java, Indian Ocean, Gulf of Thailand. L. pacificum—warm water region to temperate—Mediterranean, Indian Ocean, South Atlantic. Remarks: Lioloma elongatum is readily distinguished in LM by the coarser areolae (Table 65), the single apical spine, and the long tapering foot pole (Plate 53); L. pacificum is distinguished by the blunt, not especially widened head pole with two small spines and the more or less distinct widening near the foot pole (Plate 53), and L. delicatulum by the delicate areolation (Table 65), and in valve view, the wide head-pole.

The diatom we identify as Lioloma elongatum has the morphological features illustrated for T. elongata in Van Heurck (1880-1885) and described and illustrated for T. vanhoeffenii in Heiden & Kolbe (1928).

Genus Thalassionema Grunow ex Mereschkowsky 1902 (Plates 55, 56, and 57, Table 66)

Type: Thalassionema nitzschioides (Grunow) Mereschkowsky Basionym: Synedra nitzschioides Grunow.

Synonym: Thalassiothrix nitzschioides (Grunow) Grunow in Van Heurck. References: Grunow, 1862, p. 403, Plate 5, Figs. 18a and 18b; Grunow, 1863, p. 140, Plate 5, Figs. 18a-18c; Greville, 1865a, p. 4, Plate 5, Figs. 5 and 6; Cleve & Grunow, 1880, p. 109; Van Heurck, 1880-1885, Plate 37, Figs. 11-13, Plate 43, Figs. 7-10; Mereschkowsky, 1902, p. 78, 1903

Thalassionema

T. bacillare T frauenteldii

PLATE SS Thalassionema bacillare: (a) colony in valve view. Scale bar = 20 /im; (b) valve view with marginal structure. Scale bar = 10 /im. Thalassionema frauenfeldii: (a) colony in girdle view. After Cupp (1943); Scale bar = 20 /im. (b) valve view with marginal structure and apical spine. Scale bar =10 /im.

PLATE 56 Scanning electron micrographs. (1) Thalassionema javanicum: external view of pointed valve end, apical spine, one marginal row of areolae, and elaborate vela. (2) Thalassionema nitzschioides: external view of rounded valve end, wide sternum, one marginal row of areolae, and elaborate vela. (3) Thalassionema bacillare: external view of slightly dilated cell end, wide sternum, one marginal row of areolae and elaborate vela. (4) Thalassionema pseudonitzschioides: external view of the more narrow valve end, base of apical spine, wide sternum, one marginal row of areolae, and less elaborate vela (reduced ?). (5) Thalassionema frauenfeldii: external view with one marginal row of areolae crossed by a simple bar; (a) tapering end with apical spine; (b) part of valve with wide sternum. Scale bar = 1 /xm.

pp. 91 and 178; Heiden 8c Kolbe, 1928, p. 564, Plate 6, Fig. 121; Meister, 1932, p. 25, Fig. 52; Cupp, 1943, p. 182, Fig. 133; Kolbe, 1955, p. 178; Hustedt, 1959, pp. 244 and 247, Figs. 725 and 727; Hasle 8c Mendiola, 1967; Drebes, 1974, p. 103, Fig. 85c; Schuette 8c Schräder, 1982; Hallegraeff, 1986, pp. 60-65.

Thalassionema

T. nitzschioides

T. pseudonitzschioides

T. javanicum

PLATE 57 Thalassionema nitzschioides: (a) chain in girdle view. Scale bar = 20 p.m; (b) valves showing size variation and marginal areolae. Scale bar = 10 p,m. Thalassionema javanicum: valve with apical spine and areolae. Scale bar = 10 /im. Thalassionema pseudonitzschioides: valves, showing size variation, apical spine, and marginal areolae. Scale bar =10 p.m.

TABLE 66 Morphometric Data of Thalassionema spp.

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